Health Guide: Cataracts

Cataracts

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Definition

A degenerative opacity of the lens that leads to loss of vision.

Clinical Signs

May observe the following:

Initially be seen as a white dot behind pupil.

Progression of a grey or milky white discoloration of the pupil(s).

Etiology

Cataracts, a white/grey discoloration of the pupil(s), can occur due to trauma, inflammation, systemic disease, and aging.

They are typically bilateral, but may progress more in one eye than the other.

A transient form of cataracts has been know to happen frequently in rodents when they are placed under anesthesia. It is believed to be due to the changing composition and temperature of the aqueous humor of the eye while open and unblinking. This does resolve once the animal recovers.²

Cataracts occuring with age may be due to changes in protein, accumulation of water and edema, and the disruption of normal fibers in the lens.

As the condition of the cataracts advance, it causes the lens to become cloudy which leads to blindness.

There can also be other causes that can contribute to the early formation of cataracts, such as long term use of corticosteroids or phenothiazines, or diseases such as diabetes, microphthalmia, and hypertension.

Photo examples of cataract formation have been provided in the following figures.

Fig. 1: Cataracts and case history
Fig. 2: Cataracts in hairless rat.
Fig. 3 Case history of cataract in 20 month old siamese rat.
Fig. 4 Visit Lisa Jenny’s page for photo of rat showing initial cataracts.

Diagnostics

Visualized by ophthalmoscopy

Treatment

Rat’s, having poor vision to start with, adapt well. Treatment should be directed at correcting underlying conditions if possible.

Nursing Care

Provide for safe environment. Reduce chances of falls from heights by keeping cage levels to a minimum.

Allow the rat to become familiar with cage surroundings. Prevent redesigning or moving interior cage accessories around.

Keep water bottles and food dishes in same familiar area of cage.

Outcomes

Underlying conditions corrected.

No advancement of condition noted.

Prevention

Early treatment of conditions or illnesses associated with the formation of cataracts may prevent or delay their onset.

Posted on June 28, 2003, 09:59, Last updated on May 31, 2008, 10:58 | Eyes